License Committee Report for July 2007

John Cowan cowan at
Tue Jul 31 21:18:32 UTC 2007

Wilson, Andrew scripsit:

> Chris, as you know, the actual compatibility matrix for LGPL is
> really much more complicated.  LPGLv3 is compatible with GPLv3,
> with LGPLv2-or-later and GPLv2-or-later, BSD, and can even be linked
> to proprietary code, but it is not compatible with LGPLv2-only or
> GPLv2-only (unless it's GPLv2 with the runtime or classpath exceptions).
> This is (IMO) a really hokey situation, where LGPLv3 is compatible
> with non-free SW but not with free SW under GPLv2/LGPLv2.

It's not as bad as you think.  There are two kinds of derivative works
made from LGPLed code: in LGPLv2-speak, they are "works based on the
library" and "works that use the library".  The corresponding LGPLv3 terms
are "works based on the Program" and "Combined Works", respectively.

The compatibility matrix you speak of refers only to the first kind:  you
cannot add a LGPLv3-only module to an LGPLv2-only library.  However, you
are entirely free to make use of an LGPLv2 or LGPLv3 or LGPLv2-or-later
library from any kind of program, whether under an FSF license, another
FLOSS license, or a proprietary license, provided you obey the basic
constraints (allowing the user to replace the library with new versions,

John Cowan  cowan at
Arise, you prisoners of Windows / Arise, you slaves of Redmond, Wash,
The day and hour soon are coming / When all the IT folks say "Gosh!"
It isn't from a clever lawsuit / That Windowsland will finally fall,
But thousands writing open source code / Like mice who nibble through a wall.
        --The Linux-nationale by Greg Baker

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